The use of spring clips as a connecting member to urge the fuel injector toward its sealing surface after assembly is standard practice in a multi-port fuel injection (MPFI) system. However, conventional MPFI spring clips are not suitable for use in high pressure direct injector (DI) applications in which a DI fuel injector is mounted in the engine cylinder head directly above the combustion chamber since the nozzle end of the DI injector is directly exposed to the high combustion pressures which occur in the combustion chamber. In the case of a DI injector, a higher, positive load must be applied to the injector to hold it in place against the higher pressures and to ensure that it remains sealed against leakage of exhaust gases from the combustion chamber. In a high pressure DI system, each injector is typically individually mounted on the cylinder head by means of a clamp or a tab. This procedure of individually mounting each fuel injector adds substantially to the manual labor cost of the assembly of the engine.
U.S. Pat. No. 5,970,953, the disclosure of which is incorporated herein by reference, describes a fuel injector clip that is intended for high pressure applications. The clip disclosed in the '953 reference is disclosed as being compressed beyond its maximum yield point when the injector is installed. Therefore the maximum force the spring can exert to assure that the injector remains seated is limited and may not be suitable in a DI injector application. Copending, commonly assigned application Ser. No. 09/329,508, filed Jun. 10, 1999, for INTEGRATED FUEL DELIVERY MODULE FOR DIRECT INJECTION, the disclosure of which is incorporated herein by reference, discloses a spring more suitable for a DI injector application. The application discloses a module type fuel delivery system for direct fuel injection into the combustion chambers of multiple cylinders of an engine that includes a common fuel rail and a plurality of spaced fuel feeder passages extending from the fuel rail. Each feeder passage is provided with an open ended mounting recess for receiving a DI fuel injector. Between the mounting recess and the injector is positioned a spring for loading the injector against its seat in the cylinder head above the combustion chamber. The spring load seats the injector against the force of combustion pressure during engine operation.
While the module type fuel delivery system disclosed in application Ser. No. 09/329,508 does not require that each injector be individually mounted to the cylinder head first, the labor time associated with hand assembling each spring between the recess of the feeder passage and the injector immediately before the module is installed on the engine can be substantial. Moreover, assembling the individual injectors to the fuel rail immediately before engine installation does not lend itself to an easy way of testing for flow and leakage of the fuel rail/injectors module before the module is installed on the engine.
Therefore, there is an ongoing need for a device that allows high pressure fuel injectors to be conveniently pre-assembled with a fuel rail prior to its connection to an engine cylinder head. The present invention addresses this need.